+ /* Check for 5-level paging */ + if (!(machdep->flags & VM_5LEVEL)) { + int l5_enabled; + if ((string = pc->read_vmcoreinfo("NUMBER(pgtable_l5_enabled)"))) { + l5_enabled = 1; + free(string); + } else if (kernel_symbol_exists("__pgtable_l5_enabled")) + readmem(symbol_value("__pgtable_l5_enabled"), KVADDR, + &l5_enabled, sizeof(int), "__pgtable_l5_enabled", + FAULT_ON_ERROR); + + if (l5_enabled) + machdep->flags |= VM_5LEVEL; + }

+ /* Check for 5-level paging */ + if (!(machdep->flags & VM_5LEVEL)) { + int l5_enabled; + if ((string = pc->read_vmcoreinfo("NUMBER(pgtable_l5_enabled)"))) { + l5_enabled = 1; + free(string); + } else if (kernel_symbol_exists("__pgtable_l5_enabled")) + readmem(symbol_value("__pgtable_l5_enabled"), KVADDR, + &l5_enabled, sizeof(int), "__pgtable_l5_enabled", + FAULT_ON_ERROR); + + if (l5_enabled) + machdep->flags |= VM_5LEVEL; + }

----- Original Message ----- > > Hello Dou, > > This patch was failing on most -- but not all -- of my test dumpfiles, because of > fatal read or seek errors during session initialization. > > As it turns out, the "l5_enabled" local variable needs to be zeroed-out, because > if neither the "if" or the "else" are true, it uses whatever old stack garbage > that l5_enabled contains: > > > + /* Check for 5-level paging */ > > + if (!(machdep->flags & VM_5LEVEL)) { > > + int l5_enabled; > > + if ((string = pc->read_vmcoreinfo("NUMBER(pgtable_l5_enabled)"))) { > > + l5_enabled = 1; > > + free(string); > > + } else if (kernel_symbol_exists("__pgtable_l5_enabled")) > > + readmem(symbol_value("__pgtable_l5_enabled"), KVADDR, > > + &l5_enabled, sizeof(int), "__pgtable_l5_enabled", > > + FAULT_ON_ERROR); > > + > > + if (l5_enabled) > > + machdep->flags |= VM_5LEVEL; > > + } > > I'll fix that and retest. It still fails on 4.17 and later kernels that have this in their VMCOREINFO: NUMBER(pgtable_l5_enabled)=0 You need to do atoi(string) to get its value. I'll fix that and retest again... Dave

> > Thanks, > Dave > > > > > > ----- Original Message ----- > > Currently, Crash only enable support for kernel-only 5-level page tables > > by > > entering the command line option "--machdep vm=5level". Since Linux 4.17, > > the Linux kernel can be both 4level and 5level page tables. This command > > line > > can't work well for this. > > > > Using the "pgtable_l5_enabled" to detect whether the kernel proper for 5 > > level > > page tables automatically. Also move the 5-level paging setup from > > machdep_init(PRE_GDB) > > to machdep_init(POST_RELOC). > > > > Signed-off-by: Dave Anderson <anderson(a)redhat.com&gt; > > Signed-off-by: Dou Liyang <douly.fnst(a)cn.fujitsu.com&gt; > > --- > > Changelog v1 --> v2 > > > > 1. Make it support live systems suggested by Dave > > 2. Using __pgtable_l5_enabled for check. > > 3. Do some tests in both kdump(5level and 4level) and virsh dump(5level > > and > > 4level) > > --- > > x86_64.c | 56 +++++++++++++++++++++++++++++++++++++------------------- > > 1 file changed, 37 insertions(+), 19 deletions(-) > > > > diff --git a/x86_64.c b/x86_64.c > > index 6d1ae2f..07b6aa9 100644 > > --- a/x86_64.c > > +++ b/x86_64.c > > @@ -294,25 +294,6 @@ x86_64_init(int when) > > machdep->machspec->pgdir_shift = PGDIR_SHIFT; > > machdep->machspec->ptrs_per_pgd = PTRS_PER_PGD; > > break; > > - > > - case VM_5LEVEL: > > - machdep->machspec->userspace_top = USERSPACE_TOP_5LEVEL; > > - machdep->machspec->page_offset = PAGE_OFFSET_5LEVEL; > > - machdep->machspec->vmalloc_start_addr = VMALLOC_START_ADDR_5LEVEL; > > - machdep->machspec->vmalloc_end = VMALLOC_END_5LEVEL; > > - machdep->machspec->modules_vaddr = MODULES_VADDR_5LEVEL; > > - machdep->machspec->modules_end = MODULES_END_5LEVEL; > > - machdep->machspec->vmemmap_vaddr = VMEMMAP_VADDR_5LEVEL; > > - machdep->machspec->vmemmap_end = VMEMMAP_END_5LEVEL; > > - if (symbol_exists("vmemmap_populate")) > > - machdep->flags |= VMEMMAP; > > - machdep->machspec->physical_mask_shift = > > __PHYSICAL_MASK_SHIFT_5LEVEL; > > - machdep->machspec->pgdir_shift = PGDIR_SHIFT_5LEVEL; > > - machdep->machspec->ptrs_per_pgd = PTRS_PER_PGD_5LEVEL; > > - if ((machdep->machspec->p4d = (char *)malloc(PAGESIZE())) == NULL) > > - error(FATAL, "cannot malloc p4d space."); > > - machdep->machspec->last_p4d_read = 0; > > - machdep->uvtop = x86_64_uvtop_level4; /* 5-level is optional > > per-task > > */ > > } > > machdep->kvbase = (ulong)PAGE_OFFSET; > > machdep->identity_map_base = (ulong)PAGE_OFFSET; > > @@ -346,6 +327,43 @@ x86_64_init(int when) > > break; > > > > case POST_RELOC: > > + /* Check for 5-level paging */ > > + if (!(machdep->flags & VM_5LEVEL)) { > > + int l5_enabled; > > + if ((string = pc->read_vmcoreinfo("NUMBER(pgtable_l5_enabled)"))) { > > + l5_enabled = 1; > > + free(string); > > + } else if (kernel_symbol_exists("__pgtable_l5_enabled")) > > + readmem(symbol_value("__pgtable_l5_enabled"), KVADDR, > > + &l5_enabled, sizeof(int), "__pgtable_l5_enabled", > > + FAULT_ON_ERROR); > > + > > + if (l5_enabled) > > + machdep->flags |= VM_5LEVEL; > > + } > > + if (machdep->flags & VM_5LEVEL) { > > + machdep->machspec->userspace_top = USERSPACE_TOP_5LEVEL; > > + machdep->machspec->page_offset = PAGE_OFFSET_5LEVEL; > > + machdep->machspec->vmalloc_start_addr = VMALLOC_START_ADDR_5LEVEL; > > + machdep->machspec->vmalloc_end = VMALLOC_END_5LEVEL; > > + machdep->machspec->modules_vaddr = MODULES_VADDR_5LEVEL; > > + machdep->machspec->modules_end = MODULES_END_5LEVEL; > > + machdep->machspec->vmemmap_vaddr = VMEMMAP_VADDR_5LEVEL; > > + machdep->machspec->vmemmap_end = VMEMMAP_END_5LEVEL; > > + if (symbol_exists("vmemmap_populate")) > > + machdep->flags |= VMEMMAP; > > + machdep->machspec->physical_mask_shift = > > __PHYSICAL_MASK_SHIFT_5LEVEL; > > + machdep->machspec->pgdir_shift = PGDIR_SHIFT_5LEVEL; > > + machdep->machspec->ptrs_per_pgd = PTRS_PER_PGD_5LEVEL; > > + if ((machdep->machspec->p4d = (char *)malloc(PAGESIZE())) == NULL) > > + error(FATAL, "cannot malloc p4d space."); > > + machdep->machspec->last_p4d_read = 0; > > + machdep->uvtop = x86_64_uvtop_level4; /* 5-level is optional > > per-task > > */ > > + machdep->kvbase = (ulong)PAGE_OFFSET; > > + machdep->identity_map_base = (ulong)PAGE_OFFSET; > > + > > + } > > + > > /* > > * Check for CONFIG_RANDOMIZE_MEMORY, and set page_offset here. > > * The remainder of the virtual address range setups will get > > -- > > 2.14.3 > > > > > > > > > > -- > Crash-utility mailing list > Crash-utility(a)redhat.com > https://www.redhat.com/mailman/listinfo/crash-utility > -- Crash-utility mailing list Crash-utility(a)redhat.com https://www.redhat.com/mailman/listinfo/crash-utility

----- Original Message ----- > > > At 07/12/2018 02:23 AM, Dave Anderson wrote: >> >> >> ----- Original Message ----- >>> >>> >>> ----- Original Message ----- >>>> Hi Dave, >>>> >>>> At 07/11/2018 03:33 AM, Dave Anderson wrote: >>>>> >>>>> The final phase of support would be making this work: >>>>> >>>>> static int >>>>> x86_64_task_uses_5level(struct task_context *tc) >>>>> { >>>>> return FALSE; >>>>> } >>>>> >>>>> Have you had a chance to look at how that can be done? >>>>> >>>> >>>> I have no idea to check if 5level paging is used in User-space. >>>> >>>> You gave me some methods, and I have try: >>>> >>>> -The MAP_FIXED flag >>>> -check if the contents of the page directory or p4d is 'flods' >>> >>> It would be most helpful if you can compare two tasks, one with 5-level >>> and one without, and see if there's anything obviously different. >>> (I don't know what "flods" means) >> >> Ah, sorry, you mean if the top-level page directory folds back into itself. >> >> So yes, I wonder if it would be obvious enough by checking whether the >> top-level pgd folds back into itself, and if so, 4-levels of page tables >> are in use? But if that were the case, it seems that the 5-level translation >> code would work on both types of user-space tasks. I just don't understand >> how it's supposed to work. >> > > OK, let me try to clarify if the the 5-level translation code would work > on both types of user-space tasks at first. ;-) >

> Thank you so much for you kind explanation! > > dou. Hi Dou, That leads me to this question: can you confirm that this crash patch works with a kernel that is configured with CONFIG_X86_5LEVEL, but either: (1) the kernel was booted with "no5lvl", or (2) the host hardware does not have the X86_CR4_LA57 bit set

Thanks, Dave